Apparatus for finishing gears



Sept. 10, 1940- .R. s. DRUMMOND APPARATUS FOR FINIS HING GEARS Filed June 14, 1937 'FIGJ.

FIG.2.

I VII/ INVENTOR ROBERT. S DRUMMOND ATTORNEYS BY MW IW+MA Patented Sept. 1940 v UNITED STATES PATENT OFFICE 4 Claims;

This invention relates to a method of finishing gears and apparatus therefor. It is an object of the invention to provide a novel gear finishing machine in which the gear finishing tool comprises two gear shaped elements of different finishing characteristics.

It is a further object of the invention to provide a machine in which the finishing tool may be shifted relative to the gear being finished, so

10 as to provide two diiferent finishing effects without interruption of the finishing operation. 7

It is a further object of the invention toprovide a gear finishing tool in the former two axially spaced coaxial finishing elements of different characteristics in'which the teeth of said .elements are aligned.

It is a further. object of the invention to provide agear finishing tool in the form of two axially spaced coaxial finishing elements with an interposed coaxial guiding element which will provide for continuous mesh engagement between the tool and the work, as the tool is shifted relative to the work.

Further objects will be apparent on reading the following detailed description taken in conjunction with the accompanying drawing, in

which Fig. 1 is a section through the tool carrying head of my improved gear.finishing machine, showing the engagement between my novel tool and the gear being finished;

Fig. 2 is a section through-a difierent form of finishing todL. V

The gear finishing machine to which my improved tool and shifting mechanism therefor is applied is in all respects similar to the machine previously used with a single tool. Such machine isfully shownv and described in my copending application Serial No. 3662, filedJanuary 26, 1935, 40 to which reference should be had for a complete description of the machine.

In this machine the gear. to be finished iscarried by a work carriage which is mounted for vertical movement and for horizontal translation. In operation, the tool is rotated by'a motor which is carried by a topLcarrying head and the work gear is mounted for free rotation on M two spindles 80 and BI. The work carriage which supports the spindles and BI is adapted to be so fed either manually or automatically toward the finishing tool. In a preferred form of this invention, suitable mechanism is provided which will elevate the work carrying table a predetermed amount at the end of each finishing stroke. After elevation of the work carrying table, suitable opposite direction.

'portingmember 44 by two nuts 48. The supportmechanism translates the table relative to the gear tool an amount suificlent to distribute the finishing eifect of the tool across theface of the. teeth of the work gear being finished.

At the endofthis translation, suitable switch mechanism reverses the rotation of the motor driving the finishing tool and also reverses the r0- tation of a second motor which drives the work carrying table in translatory motion and causes the work carrying .table to be translated in the The present invention is directed particularly to a modified form of tool carrying head and a modifiedform of finishing tool cooperating there-. with. a g

As shown in Fig. l, a tool carrying head generally indicated at III has a main body portion I2 which is mounted'for adjustment about a vertical axis. A finishing tool generally indicated by the numeral I I is composed, as shown in Fig. 1, of three elements, a roughing element R, a finishing element F and an intermediate guiding dummy D. These threeelements are all in the form of gears with teeth conjugate to the teeth of the work gear to be finished. These elements are axially spaced and are coaxial and are'arranged so that their teeth are continuous from side-to side of the tool, or are, in other words, in alignment. The finishing tool II is clamped to a sup- 30 ing member 44 has keys 45 on an internal bore therethrough. H These keys 45 are adapted to be received within a key-way 41 formed on the periphery of a driving spindle I4. This spindle I4 is hollow and has an axially extending slot 46 formed therein. The spindle I4 is journaled for rotation in the tool carrying head In and suitable bearings I6 are provided therefor. Rigidly secured to the shaft I4 is a gear member 22 which meshes with. a gear 24. The gear 24 is journaled for rotation in the head member ID and suitable bearings '28 are provided therein. The shaft 26 which carries thegear 24 has at one end thereof a bevel gear 30 whichvmeshes. with a second bevel gear 32. The gear 32 is carried by a shaft 34' suitably journaled in the head III and provided with bearings 36. A driving motor (not shown) is connected to the shaft 34 and drives the tool I I through the gears just described. A*second supporting member I8 is detachably mounted on the frame I2 and is adapted to receive in a suitable bearing the endof the spindle I4, opposite to the end which carries the gear 22.

Means for shifting the tool II axially iscprovided and comprises a rod 40 received within the 55 able mechanism is provided at the opposite end of the rod 40 and comprises a channeled head member 50 and cooperating bell crank lever 52 pivoted at 5| and provided with an operating arm- 54 and a manual lever 56. The rod 40 projects through a closure cap 53 which is provided on the head l2. As can be seen, when the lever 56 is rotated in a clockwise direction, the rod 40 will be shifted axially to the right and will move the gear so that the roughing tool R moves out of engagement with the work W and the finishing tool F comes into operative engagement with the work gear. In orderthat this shifting of the tool H may be accomplished while the tool and work are rotating, the dummy D is provided. This will insure constant mesh between the tool I l and the work W as can be seen in thisfigure. The dummy D is of slightly smaller diameter and its sole purpose is to insure constant mesh as the tool is shifted relative to .the work. The

dummy; will have no finishing effect on the teeth of the work gear.

In some cases, it is possible to omit the dummy 1 D and'I have illustrated such modification in Fig. 2. In this figure the gear II is composed of a finishing tool and a roughing tool. These tools are axially spaced so that when one is in operative engagement with the work, the other will be out of contact with the work. These two elements F and R, however, are sufiiciently close together so that before one is out of guiding mesh with the work, the other will bebrought into mesh with the work. ,This tool is intended and adapted for use in the same tool carrying head l0 illustrated in Fig. 1.

By the above described construction, I have provided for more rapid finishing of gears. In this type of machine, a roughing tool ordinarily is a tool inthe form of a gear-having gashes formed on the faces of 'the teeth. These gashes leave intermediate lands and these lands have sharp cutting edges at their top comers. It is these cutting edges which, due to the crossed axes relationship of the tool .and work, take fine cuts or shavings from the face of the teeth of the gear being finished. A roughing tool diifers from a finishing tool in that the gashes are wider, while the width of land intermediate the gashes is maintained at about the same width. This roughing tool is adapted to remove stock from the work gear more rapidly than a finishing tool, but

is not quite so accurate as the finishing tool. In

a finishing tool, the width of lands and grooves are substantially equal, and this tool is adapted to finish a work gear to a high degree of accuracy.

In my improved construction, as will be readily seen, it is possible to mesh a work gear W with a roughing tool. This is illustrated in Fig. 1. The motor driving the tool is then started and the roughing gear drives the work gear by the meshing engagement therewith.- The work gear is translated in a plane parallel to the axis of the finishing tooland preferably in a direction parallel to its own axis. It is possible, however, to translate the work gear in the defined plane in any direction otherthan a direction parallel. to the axis of the finishing tool. After a predetermined numberof strokes have been taken by the roughing gear, the lever 56 is manipulated and the finishing tool is abruptly shifted so that the finishing tool comes into meshing engagement with the work. As the dummy D is provided between the finishing and roughing portions of the 5 tool, this dummy will insure continuous meshing engagement between the tool and the work during this shifting. In cases where the dummy is omitted, the roughing portion R. and the finishing portion F are spaced sufilciently close together so that at no time'during this shifting movement are the work gear and the finishing tool out of guiding mesh. It will thus be seen that the roughing gear serves-a function not only of providing a rough finish to the work but also a function of guiding the complete tool during the shifting movement from roughing to finishing portion of the tool.

By this means it is possible to mount the work gear on the spindles and BI and to finish it in what amounts to a single operation, rather than providing separate roughing and finishing gears.

In this connection it should be noted that the use of a roughing and finishing tool is very advantageous but is oftentimes not used because of .the delay which would be involved in mounting the work gear relative to a roughing tool, carrying out the roughing operation, removing the. work gear, mounting it in a difierent machine in cooperating relation with the finishing gear, carrying out the finishing operation and removing the finished gear. By the use of a combined roughing and finishing gear as taught in this application, it is possible to retain the advantages of preliminary rough finishing and final accurate finishing without necessitating the dismounting of the} work gear. By the use of a roughing and finishing gear' in a single machine, the finishing gear is called upon to do only finishing work on a gear which is only roughly finished, and the life of the finishing gear is therefore greater than in cases where it is used for both preliminary and final finishing.

While I have illustrated and described two specific embodiments of my invention, it will be apparent to those skilled in the art that various additions, modifications, omissions and substitutions may be made which will be within the spirit and scope of my invention as defined in the accompanying claims.

What I claim as my invention is:

1. A multiple rotary tool for use in a gear finishing machine comprising a first gearshapedelement having teeth provided with cutting edges and adapted to impart a preliminary finish to a gear being finished, a second gear shaped element axially spaced from said first portion and having teeth provided with cutting edges and adapted to impart a final finish to the gear being finished, and a toothed guiding dummy having smooth teeth of reduced size' interposed between said first and second elements,the teeth of s d first and second elements and said dummy be 2. A gear finishing machine comprising a spindle ,for mounting a gear to be finished, aspindle for mounting a finishing tool, the axes of said spindles being crossed at an angle of less than 30, means for rotating one of said spindles, the other spindle being mounted for free rotation, means for slowly translating one of said spindles relative to the other in a plane parallel to the axis of the other to distribute the g aligned.

finished, and means operable during rotation of said spindles for abruptly shifting one of said spindles relative to the other, in a plane parallel to the axis of the other and in a direction difi'erent from said slow translation, said finishing tool being of generally gear form, and comprising a first gear shaped element provided with teeth adapted to impart a preliminary finish to a gear being finished, a second gear "shaped element axially spaced from said first portion and having teeth adapted to impart a final finish to the gear being finished, anda toothed guiding dummy interposed between said first and second elements,

the teeth of said first and second elements and said dummy being aligned, the shifting of said spindle transferring the engagement of the work from one to the other of said elements at will.

3. A gear finishing machine comprising a spindle for mounting a gear (to be finished, a spindle for mounting a finishing tool, the axes of said spindles being crossed at an angle of less than 30", means for rotating one of said spindles, the'other spindle being mounted for free rotation," m'ean,s for slo'wly translating one of said spindles-relative to the other in a plane parallel to the axis of the other" to distribute the finishing action across the face of the gear being finished, and, means for abruptly shifting one of said -spindles relative to the other, during rotation thereof in a direction different from said slow translation, said finishing tool being of generally gear form, and comprising a pair of coaxial gear shaped elements provided with teeth with diiferent finishing characteristics, said elements being assembled in axially spaced relation, the spacing being such that when the said abrupt shifting takes place, one element will enter into loose mesh with the gear being finished before the other element is out of mesh with the gear being finished, the shiftingof said spindle transferring the engagement of the work from one to the other of said elements at will.

4. A gear finishing machine comprising a spindle for mounting a gear to be finished, a spindle for mounting a finishing tool, the axes of said spindles being crossed at an angle of less than 30, means for rotating one of said spindles, the other spindle being mounted for free rotation, means for slowly translating said first mentioned spindle relative to the other in a plane parallel to the axis of the other to distribute the finishing action across the face of the gear being finished, and means for abruptly shifting said second mentioned spindle relative to the other, in a plane parallel to the axis of the other and in a direction different from said slow translation, said finishing tool being of generally gear form, and comprising a plurality .of axially spaced gear shaped elements, each having teeth adapted to perform. different finishing operations on a gear to be finished, a toothed guiding dummy interposed between adjacent elements having teeth of reduced 'size, the teeth of said elements and said dummy being aligned, the shifting of said spindle transferring the engagement of the work from oneto another of said elements at will, said toothed dummy eflecting rotation of both spindles while said gear is'out of mesh with said gear shaped elements. v

ROBERT S; DRUMIMOND. 

